In a package-on-package (PoP) semiconductor device, multiple semiconductor packages are stacked and secured to one another. For example, a package including a memory chip can be stacked on a package including a logic chip. With a conventional PoP structure, the available surface area for laying out a circuit on the package substrate is limited. Thus, interference between signals can occur when circuit paths are positioned too close to one another. One solution to this problem is to increase the number of layers in a multi-layered substrate. However, this solution increases manufacturing costs. Thus, it would be desirable to limit interference between circuit paths without increasing the number of layers in a multi-layered substrate.